1 | /* |
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2 | * IMFS Directory Access Routines |
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3 | * |
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4 | * COPYRIGHT (c) 1989-1999. |
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5 | * On-Line Applications Research Corporation (OAR). |
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6 | * |
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7 | * The license and distribution terms for this file may be |
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8 | * found in the file LICENSE in this distribution or at |
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9 | * http://www.rtems.com/license/LICENSE. |
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10 | * |
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11 | * $Id$ |
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12 | */ |
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13 | |
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14 | #if HAVE_CONFIG_H |
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15 | #include "config.h" |
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16 | #endif |
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17 | |
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18 | #include "imfs.h" |
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19 | |
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20 | #include <string.h> |
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21 | #include <dirent.h> |
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22 | |
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23 | /* |
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24 | * imfs_dir_open |
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25 | * |
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26 | * This rountine will verify that the node being opened as a directory is |
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27 | * in fact a directory node. If it is then the offset into the directory |
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28 | * will be set to 0 to position to the first directory entry. |
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29 | */ |
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30 | |
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31 | int imfs_dir_open( |
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32 | rtems_libio_t *iop, |
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33 | const char *pathname, |
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34 | int oflag, |
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35 | mode_t mode |
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36 | ) |
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37 | { |
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38 | IMFS_jnode_t *the_jnode; |
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39 | |
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40 | /* Is the node a directory ? */ |
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41 | the_jnode = (IMFS_jnode_t *) iop->pathinfo.node_access; |
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42 | |
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43 | if ( the_jnode->type != IMFS_DIRECTORY ) |
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44 | return -1; /* It wasn't a directory --> return error */ |
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45 | |
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46 | iop->offset = 0; |
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47 | return 0; |
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48 | } |
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49 | |
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50 | /* |
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51 | * imfs_dir_read |
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52 | * |
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53 | * This routine will read the next directory entry based on the directory |
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54 | * offset. The offset should be equal to -n- time the size of an individual |
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55 | * dirent structure. If n is not an integer multiple of the sizeof a |
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56 | * dirent structure, an integer division will be performed to determine |
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57 | * directory entry that will be returned in the buffer. Count should reflect |
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58 | * -m- times the sizeof dirent bytes to be placed in the buffer. |
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59 | * If there are not -m- dirent elements from the current directory position |
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60 | * to the end of the exisiting file, the remaining entries will be placed in |
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61 | * the buffer and the returned value will be equal to -m actual- times the |
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62 | * size of a directory entry. |
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63 | */ |
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64 | |
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65 | ssize_t imfs_dir_read( |
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66 | rtems_libio_t *iop, |
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67 | void *buffer, |
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68 | size_t count |
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69 | ) |
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70 | { |
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71 | /* |
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72 | * Read up to element iop->offset in the directory chain of the |
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73 | * imfs_jnode_t struct for this file descriptor. |
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74 | */ |
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75 | rtems_chain_node *the_node; |
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76 | rtems_chain_control *the_chain; |
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77 | IMFS_jnode_t *the_jnode; |
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78 | int bytes_transferred; |
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79 | int current_entry; |
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80 | int first_entry; |
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81 | int last_entry; |
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82 | struct dirent tmp_dirent; |
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83 | |
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84 | rtems_filesystem_instance_lock( &iop->pathinfo ); |
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85 | |
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86 | the_jnode = (IMFS_jnode_t *)iop->pathinfo.node_access; |
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87 | the_chain = &the_jnode->info.directory.Entries; |
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88 | |
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89 | /* Move to the first of the desired directory entries */ |
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90 | |
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91 | bytes_transferred = 0; |
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92 | first_entry = iop->offset; |
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93 | /* protect against using sizes that are not exact multiples of the */ |
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94 | /* -dirent- size. These could result in unexpected results */ |
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95 | last_entry = first_entry |
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96 | + (count / sizeof( struct dirent )) * sizeof( struct dirent ); |
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97 | |
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98 | /* The directory was not empty so try to move to the desired entry in chain*/ |
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99 | for ( |
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100 | current_entry = 0, |
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101 | the_node = rtems_chain_first( the_chain ); |
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102 | current_entry < last_entry |
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103 | && !rtems_chain_is_tail( the_chain, the_node ); |
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104 | current_entry += sizeof( struct dirent ), |
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105 | the_node = rtems_chain_next( the_node ) |
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106 | ) { |
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107 | if( current_entry >= first_entry ) { |
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108 | /* Move the entry to the return buffer */ |
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109 | tmp_dirent.d_off = current_entry; |
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110 | tmp_dirent.d_reclen = sizeof( struct dirent ); |
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111 | the_jnode = (IMFS_jnode_t *) the_node; |
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112 | tmp_dirent.d_ino = the_jnode->st_ino; |
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113 | tmp_dirent.d_namlen = strlen( the_jnode->name ); |
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114 | strcpy( tmp_dirent.d_name, the_jnode->name ); |
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115 | memcpy( |
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116 | buffer + bytes_transferred, |
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117 | (void *)&tmp_dirent, |
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118 | sizeof( struct dirent ) |
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119 | ); |
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120 | iop->offset += sizeof( struct dirent ); |
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121 | bytes_transferred += sizeof( struct dirent ); |
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122 | } |
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123 | } |
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124 | |
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125 | rtems_filesystem_instance_unlock( &iop->pathinfo ); |
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126 | |
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127 | return bytes_transferred; |
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128 | } |
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129 | |
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130 | |
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131 | |
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132 | /* |
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133 | * imfs_dir_close |
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134 | * |
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135 | * This routine will be called by the generic close routine to cleanup any |
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136 | * resources that have been allocated for the management of the file |
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137 | */ |
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138 | |
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139 | int imfs_dir_close( |
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140 | rtems_libio_t *iop |
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141 | ) |
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142 | { |
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143 | /* |
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144 | * The generic close routine handles the deallocation of the file control |
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145 | * and associated memory. At present the imfs_dir_close simply |
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146 | * returns a successful completion status. |
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147 | */ |
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148 | |
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149 | return 0; |
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150 | } |
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151 | |
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152 | |
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153 | |
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154 | /* |
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155 | * imfs_dir_lseek |
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156 | * |
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157 | * This routine will behave in one of three ways based on the state of |
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158 | * argument whence. Based on the state of its value the offset argument will |
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159 | * be interpreted using one of the following methods: |
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160 | * |
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161 | * SEEK_SET - offset is the absolute byte offset from the start of the |
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162 | * logical start of the dirent sequence that represents the |
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163 | * directory |
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164 | * SEEK_CUR - offset is used as the relative byte offset from the current |
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165 | * directory position index held in the iop structure |
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166 | * SEEK_END - N/A --> This will cause an EINVAL to be returned. |
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167 | */ |
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168 | |
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169 | off_t imfs_dir_lseek( |
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170 | rtems_libio_t *iop, |
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171 | off_t offset, |
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172 | int whence |
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173 | ) |
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174 | { |
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175 | switch( whence ) { |
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176 | case SEEK_SET: /* absolute move from the start of the file */ |
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177 | case SEEK_CUR: /* relative move */ |
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178 | iop->offset = (iop->offset/sizeof(struct dirent)) * |
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179 | sizeof(struct dirent); |
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180 | break; |
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181 | |
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182 | case SEEK_END: /* Movement past the end of the directory via lseek */ |
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183 | /* is not a permitted operation */ |
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184 | default: |
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185 | rtems_set_errno_and_return_minus_one( EINVAL ); |
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186 | break; |
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187 | } |
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188 | |
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189 | return 0; |
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190 | } |
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